Furniture prices have held up inflation. Photograph: Bryan Mullennix/Getty

More expensive clothing offset falling air fares and petrol prices to keep the rise in the cost of living well above the Bank of England's 2% target today.

The Consumer Prices Index (CPI) remained unchanged at 3.1% in September, the Office for National Statistics (ONS) said, driven by furniture prices and food bills.

The stubbornly high rate of inflation – which has stayed at 3.1% since July – will apply further pressure on policymakers at the Bank as they decide whether to keep interest rates at 0.5%.

But pensioners are set for a boost after today's figures showed Retail Prices Index (RPI) inflation – the measure currently used to calculate the state pension – at 4.6% last month.

This will come as a relief after last year's blow, when RPI fell into negative territory, which meant pension payments rose by only the minimum amount set – 2.5%.

The government uses RPI each September to determine the following April's rise in the basic state pension, although it has pledged a minimum rise of 2.5% or the increase in average earnings, dependent on whichever is higher.

Given that RPI is likely to be the highest, this will mean the current payment will rise by around £4.49 a week, from £97.65 to around £102.14.

This will already hit benefit payments, with the government switching to CPI this year for its calculations of forthcoming changes to support such as jobseeker's allowance, tax credits and public service pensions.

Food prices are expected to continue to rise and this, coupled with the pending hike in VAT to 20% in January, means the pressure on the cost of living is not set to ease.

The sticky rate of inflation is likely to add weight to the argument to lift interest rates – a move backed by monetary policy committee member Andrew Sentance, who has been alone in voting for an increase in rates to 0.75%.

Consumers paid more for their clothing and footwear in September, where prices rose 6.4% – the largest increase between August and September on record. The hike was driven by women's outerwear – such as winter coats – where prices rose with the new autumn season, the ONS said.

Supermarket shoppers paid more for their meat and fruit in September, which lifted the overall cost of food bills, which increased by 0.1%. But the ONS said this compared with a drop in prices a year ago, when supermarkets were rolling out sales across a range of products.

The ONS said bread and cereal prices did not show any significant movement – which suggests the impact of the droughts in Russia, and the country's subsequent ban on grain exports, was yet to filter through to British prices.

Air passengers paid less for fares in September, which fell by 27.8% between August and September – compared with a 23% drop a year ago. The largest effects came from long-haul flights, the ONS said.

An overall fall of 0.8% in petrol prices, compared with a 2.3% hike a year ago, reflected a fall of 1.1p a litre in the price of petrol this year, the ONS said.

Jonathan Loynes, chief European economist at Capital Economics, said it was the first rise in clothing and footwear inflation since 1992.

He added: "This may lead to some concerns that the constant downward pressure on high street goods prices from cheap imports seen over the last decade or more is finally coming to an end. But we suspect such conclusions would be premature.

"Our guess is that the rise is a result of some retailers starting to raise their prices ahead of the coming VAT hike – and other temporary effects may have played a part too."

Loynes added that the continued pass-through of previous falls in producer prices and import prices, coupled with the spare capacity in the economy, should mean that the underlying trend in inflation remains downwards for some time.

He said: "Overall, the stubbornness of inflation is certainly not making life easy for the Bank of England. But it is unlikely to prevent the monetary policy committee from implementing more quantitative easing if, as looks likely, it decides that the economy requires more support."